In Situ Bio-Inspired Synthesis of Gold Nanoparticles on Cellulose Fiber

We investigated the in situ synthesis of gold nanoparticles (AuNPs) on unbleached softwood kraft pulp via a green approach without any additional reducing agents or external linker molecules. The structure and properties of the AuNPs composite fibers were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The resulting cellulose fiber-AuNPs composite exhibited an obvious change in color from pale yellow to purple, wine-red and dark brown due to surface plasmon resonance of the nanogold. UV-Vis DRS and FESEM images confirmed the formation of gold nanoparticles on the fiber surface. In FTIR spectra, the intensity of a shoulder band at about 1550 to 1650 cm(-1) assigned to phenol and electron rich aromatic methoxy functional groups in lignin decreased in fiber-AuNPs composite sheets, indicating that lignin plays an essential role in cellulose fiber-based green synthesis of nanoparticles. It was also revealed that gold nanoparticles formed on the fiber were well-defined pure metallic gold, suggesting that Au3+ ions are efficiently bio-reduced to Au-0, attributed to the electron rich lignin component, and bind to the fiber surface. The preparative procedure presented here is facile and provides a simple route to synthesize and immobilize AuNPs in an environmentally friendly manner.